Process for casting slab type ingots



Sept. 9, 1969 N. H. JENSEN ETAL 3,455,809

PROCESS FOR CASTING SLAB TYPE INGOTS 5 Sheets-Sheet 1 Original Filed Jan. 20, 1966 r S m Y 0 M T H n M n my T lms /A J@ m MW m FIG. 1

Sept. 9, 1969 JENSEN ETAL 3,465,809

PROCESS FOR CASTING SLAB TYPE INGOTS Original Filed Jan. 20, 1966 5 Sheets-Sheet :2

INVENTORS NEIL-S H. JENSEN [-7 1 2 HUBERT c. SMITH URNEVS Sept. 9, 1969 JENSEN ETAL 3,465,809

PROCESS FOR CASTING SLAB TYPE INGOTS Original Filed Jan. 20, 1966 5 Sheets-Sheet /N V5 N TORS N/ELS H. JENSEN HUBERT C. SMITH ORNEYS Sept. 9, 1969 JENSEN ETAL 3,465,809

PROCESS FOR CASTING SLAB TYPE INGOTS Original Filed Jan. 20, 1966 5 Sheets-Sheet 4 INVENTORS IV/ELS H. JENSEN HUBERT C. SMITH BY %/W, %m

Sept. 9, 1969 N. H. JENSEN ETAL 3,465,809

PROCESS FOR CASTING SLAB TYPE INGOTS Original Filed Jan. 20, 1966 5 Sheets-Sheet E;

INVENTORS N/ELS H JENSEN HUBERT C. SMITH FIG 7 FIG. 8

United States Patent 3,465,809 PROCESS FOR CASTING SLAB TYPE INGOTS Niels H. Jensen, Glen Moore, and Hubert C. Smith, West Chester, Pa., assignors to Lukens Steel Company, Coatesville, Pa., a corporation of Pennsylvania Original application Jan. 20, 1966, Ser. No. 521,847, now Patent No. 3,433,286, dated Mar. 18, 1969. Divided and this application Jan. 28, 1969, Ser. No. 794,572

Int. Cl. 322d 11/06, 11/12 US. Cl. 164-82 7 Claims ABSTRACT OF THE DISCLOSURE A method for pouring a slab or ingot by pouring molten metal on a movable stool within a mold through a casting floor and moving the stool down as the molten metal is being poured. The sides of the slab are supported by downwardly moving supports. After the desired slab or ingot length is obtained, the downward movement of the side supports and the stool is reversed and, by their upward movement, the slab is raised and simultaneously stripped or exposed free of the mold components at the casting floor.

This application is a division application of application Ser. No. 521,847 filed Jan. 20, 1966, now Patent No. 3,433,286 issued Mar. 18, 1969.

Continuous casting and semi-continuous casting practices in which steel is poured as the slab is moved away from the source of molten metal being poured offers several advantages, particularly in terms of yield and in the reduction of waste. Also, such practices reduce the number of steps and amount of time ultimately required in production.

There are both mechanical and metallurgical limits to the cross-sectional dimensions of the slabs cast. Presently used concepts of continuous casting are limited to the casting of slabs no thicker than 10 to 12". The net, practical effect of attempting to cast thicker slabs by currently used methods is that metallurgical requirements imposed by temperature gradients across the slab section and longitudinal thermal stresses would require unjustifiable machine heights and economically impractical straightening devices following the curved casting section of the machine.

The objects of the present invention are to overcome the disadvantages currently encountered in continuous casting and to produce a slab or ingot of greater crosssectional dimensions than is now produced by that method.

FIGURE 1 is a sectional view taken on line I-I of FIGURE 3 showing the apparatus before pouring is commenced.

FIGURE 2 is a view similar to FIGURE 1, showing the position of the moving parts of the apparatus when pouring is substantially completed.

FIGURE 3 is a top plan sectional view of the apparatus showing one arrangement of elevator means and the connections between chains and the bottom of the stool.

FIGURE 4 is a top plan view of the supporting cooling blocks showing channels through the blocks.

FIGURE 5 is a side elevational fragmentary view of the apparatus showing a slab being poured and received by the cooling blocks and also illustrating the mold.

FIGURE 6 is a perspective view showing the arrangement of equipment used in the practice of the present invention.

FIGURE 7 is a top plan view showing the cleats with portions in ofiset relation.

FIGURE 8 is a front elevation showing water coolant following a serpentine path through the cleats.

FIGURE 9 is a side elevation showing the interfitting shoes or cleats which define a serpentine path for the coolant as it flows downwardly.

All views are schematic.

In FIGURE 1 a tundish car 1 receives the molten metal from a pouring ladle, not shown, which provides the metal to be continuously cast by our process. This tundish car is a combined receiving, holding and controlled flow distribution vessel for feeding the molten metal to mold 9. Internal details of tundish car 1 are a dividing weir 2 with an opening 4 which aids in reducing turbulence of the metal in the tundish. Tundish car 1 has wheels 3 riding on tracks 5 supported by the casting floor 7. Car 1 can be positioned directly above a mold 9. Mold 9 is preferably, but not necessarily, made of copper. Other materials such as graphite or iron can be used. A movable slab or ingot receiving stool 11 is positioned below mold 9 to receive the slab or ingot being poured. The top of stool 11 is dimensioned to fit within the mold so that the stool can be located immediately below the tundish spouts at the onset of the pouring. The base and top of the stool 11a comprise a movable support. An expendable seat 12 of iron is placed on the top 11b and secured to same by links 14 which are arranged for easy detachment when the slab or ingot is stripped from the apparatus.

Elevator means 67 in the form of flexible links are secured to the extremity of each corner arm of the base of stool 11a to raise and lower same. Each chain 67 is mounted to run on a series of toothed driven gears 21 mounted within elevator columns 19 arranged between support columns 15. A plurality of linked cooling blocks 17 are connected through cables 13 to the four sides of stool base 11a so that the blocks and the elevator means, travel coextensively with the ingot or slab as the latter is raised and lowered. The cooling blocks act as cooling support for the sides of the slab received from mold 9 and little or no uncontrolled movement between the blocks and the ingot takes place.

As seen in FIGURE 3, each elevator column 19 houses a toothed driving gear 21 which receives shaft 23 connected to a bevel gear 25 at each end. A second gear wheel 36 is journalled at the top of each column 19 for receiving chain 67. At the inner side of each elevator column 19 the four corner arms 27 of the movable support 11a are elongated to fit and ride within a recess 29 of the columns 19. The elevator drive can be placed at the top or bottom of column 19 through gears 36 or 21.

As seen in FIGURES .1 and 3, chains 67 through gears 21 are moved by bevel gears 25 and 31 so that the entire train of bevel gears are rotated simultaneously to raise and lower the four chains 67. A series of guide wheels 33 and 35 at the lower part of each support column 15 are journalled in the columns, preferably above the level of the bevel gear train mounted in elevator columns 19. A guide rail system 37 is provided at the top of each column 15 for guiding the cables or chains 13 connected to linked cooling blocks 17. Shaft 39 is turned through gear box 41 and the entire bevel gear system is powered by drive shaft 43. Alternatively, a separate motor can be provided for each elevator chain 67. It will be understood that guide wheels 33 and 35 are completely independent of the elevator gear system.

As seen in FIGURES 4 and 5, the links are shown with Wheels 76 which fit in tracks 69. It will be understood, however, that rollers or wheels similar to 76 can be supported on the tracks and the links can ride on the wheels.

Referring to FIGURE 5, the mold 9 is comprised of two parts 51 and 53, the upper and lower parts, respectively. As the slab 54 is poured and lowered it is cooled so that at least on outer skin is formed. Water is pumped through pipes 55 so that the mold, preferably constructed of copper, cools the outer surfaces of the slab or ingot to the point where it retains the shape of a slab and can be supported by the stool 11. Additional coolant can be applied through the mold 51 via pipe 91 below the level of initial skin formation, to fill the opening which occurs upon solidification of the skin of the ingot due to shrinkage of the solidified skin away from the mold walls. The lower part 53 has its lower end arc-shaped at 61 to insure that the gap between the supporting cooling blocks and the lower part 53 of the mold is minimized. The upper part 51 of the mold has water or some other coolant circulated through it with a return through pipe 63. The lower part 53 has a plurality of holes 65 for spraying water continuously on the slab '4 and cascading water on the surfaces through and between the cooling blocks 17.

In FIGURES 4 and 5 the interlocked blocks ride on tracks 69 and each link 71 has shoes 72 and 74 retained by dividing walls 73. The shoes are preferably made of steel or iron, but it will be understood that the faces of the shoes or cleats 72 in contact with the hot slab 54 can be graphite or other suitable material. As the slab or ingot 54 is lowered, the shoes 72 support same on all four sides and move with the slab or ingot until casting is completed. Each cleat assembly is channeled so that water can cascade through the channels and cool the slab as it is being lowered.

The shape and arrangement of cleats or shoes 72 and 74 are shown clearly in FIGURES 7-9. To obtain positive and uniform cooling of the slab it is important to design the cleats to be effective cooling as well as supporting components. The dividing walls 73 are offset to break up the water stream right to left (see FIGURES 7 and 8) and the centrally located extensions on 72 and 74 divert the flow from front to back (see FIGURE 9) giving the water a cascading effect through the cleats. The extensions of shoes 72 and 74 extend longitudinally the full length of the cooling blocks.

Additional water is supplied to the cleat assemblies below the mold by sprays through pipe systems 90 having spray heads 92. Water can be collected in a sump at the base of the machine and is recirculated through a cleaning and cooling system (not shown). The area below the casting floor can be enclosed and adequate exhaust can be provided.

The stool 11 can be designed that the top portion 11b car have a concave upper surface. Concurrentl, expendable seat 12 can have a matching convex bottom surface to mate with 1112 to provide a variation of the aforementioned linking of seat 12 onto stool portion 11b. In a similar consideration of variations to earlier mentioned cooling and protective designs, there can be means provided in mold 9 for inert gas shielding of the stream of molten metal flowing from tundish 1 by the introduction of a series of small holes through the mold wall near the top of part 51 of mold 9. These holes and the necessary gas feed pipe system are not shown but can be readily visualized as an added feature in FIGURE 5. Also, through other feed pipes, not shown but readily visualized in FIGURE 7, an exothermic material, in a physical form conductive to easy flowing, can be fed through the walls of mold 9 or between the top of mold 9 and the bottom of tundish 1 to form a cover or blanket over the molten metal surface of slab 54. In FIGURE 5 the location of these exothermic material feed pipes would be through the walls of part 51 near the upper end or directly above the top of part 51. To one versed in the skill or art of casting metals it will be appreciated that the addition of an exothermic material, as a cover over the top surface of the slab after molten metal has stopped flowing into the mold, will retard cooling from the exposed top surface of the slab and will result in a flatter freezing pattern at the top end of the slab and increase sound metal yield of the slab.

In FIGURE 6, a design for operating a plurality of casting operations is shown. The casting floor 7 is an elevated platform housing a number of casting machines. An overhead crane system includes a ladle crane 83, tracks 5 for a tundish car 1, a gantry crane for moving the mold guide 9 and a stripper guide 87. A stripper crane 89 is used to remove the cast slabs or ingots at which time the stool is concurrently, gradually, raised, the mold 9 being replaced by a stripper guide 87.

FIGURE 6 shows one embodiment of a design or floor layout of equipment which will allow repetitive operations, on a regular basis, of the total process of casting slab type ingots of such length and weight and including molten metal from one or more pouring ladles which cannot now be produced by any other continuous casting process. The key feature in this new process is that the cast slab or ingot sections can be greater than 12' thick. The casting floor 7 is an elevated platform capable of housing one or more casting machines. One casting machine is shown in FIGURE 6. An overhead crane system includes a ladle crane 83, tracks for a tundish car 1, a gantry crane 85 for moving the mold 9 and stripper guide 87. Another overhead crane system, a stripper crane 89, is used to remove the cast slabs from above the casting machine to cooling, storage or transfer positions elsewhere on the floor 7. This stripper crane '89 is used, in this sequence during the stripping operation to remove mold 9 from on top the casting machine, place stripper guide 87 over top of casting machine to provide support for the still hot and plastic slab or metal as it is raised in the casting machine by the upward movement of stool 11. As the slab rises out of the casting machine, the stripper crane 89 is clamped to the upper end of the slab and guides, lifts, and supports the slab until it is high enough for the bottom plate 12 to be freed from stool part 11b and then the slab, in vertical position is moved away from the casting machine. After the cast slab is removed from the casting machine, a new expendable seat 12 is placed in position on stool part 11b, the mold 9 is conditioned and placed back into position on top of the casting machine, the stripper guide 87 has also been removed as soon as the slab 54 is removed, the tundish car 1 is repositioned over the mold, the cooling systems are cleaned and checked for performance and the machine is ready to repeat the continuous casting operation as soon as the ladle crane 83 moves into position over the tundish 1 with a ladle of molten metal. This description will be understood to be adaptable to many variations of layout in plan or elevation of the design shown in FIGURE 6.

While slabs or ingots of smaller cross sections can be cast according to the present invention, the most significant advantages are realized in casting slabs of larger cross-sections, i.e. those generally rectangular in configuration with minimum dimensions of about 15 by 30 inches. Because there is, at present, no other method which can cast slabs with these large rectangular dimensions in lengths of more than After beginning pouring, the initial movement of the stool can be upwardly so as to break loose, by compression, the partially cast ingot. Also, at any time the normal downward motion of the stool and ingot can be reversed and the movement of the loaded stool can be made cyclical to facilitate the movement of the slab being formed.

Salt, particularly metal salts such as sodium chloride, barium chloride, magnesium chloride and other wellknown materials can be used to lubricate passage of the slab through the mold and to fill the gaps caused by metal shrinkage. The salt also acts as a mold wash and functions as a heat extractant.

It will be understood that a conventional vibrating device can be connected to the mold 9 to promote slippage between the mold and the slab or ingot 54.

Having thus described our invention, what is claimed 1. The method of casting a slab from a casting floor, comprising pouring molten metal on a stool located within a mold, allowing the metal to partially solidify, lowering the stool and the accumulating mass of cast metal below said floor while continuing to pour molten metal and cooling same to form a slab, supporting the sides of the downwardly moving slab for a predetermined distance with downwardly moving wall supports after the slab passes through the mold, terminating pouring and thereafter raising the slab and stripping same through the casting floor.

2. The method of claim 1, wherein a cooling medium is supplied to the downwardly moving slab and wall supports to accelerate freezing and heat extraction from the metal slab, and to provide lubrication between the slab and the support and to cool the supports.

3. The method of claim 2 wherein the cooling medium is cascaded down the slab and wall supports, the cooling 20 medium being applied from level below the mold.

4. The method of claim 1, wherein the slab is cast while the stool is moved downward and then the solidified slab is raised on the stool to the casting floor level by an upward movement of the stool and supporting parts, through the casting floor by lifting same from a point above the floor.

References Cited UNITED STATES PATENTS 1,385,595 7/1921 Van Ranst 164274 X 2,696,646 12/ -4 Loewenstein 164--82 3,283,368 11/1966 Homan 164-282 3,333,627 8/1967 Forster 164282 FOREIGN PATENTS 259,519 6/1949 Switzerland.

OTHER REFERENCES J. SPENCER OVERHOLSER, Primary Examiner R. SPENCER ANNEAR, Assistant Examiner Metal Industry, Aug. 1, 1947, TS 200. M586, pp. 83-

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,465 ,809 September 9 1969 Niels H. Jensen et a1 It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 1, "on" should read an line 49, "car" should read can same line 49, "Concurrentl" should read T? Concurrently line 62, "Figure 7" should read Figure l line 63, "conductive" should read conducive Column 5 line 21, cancel "level".

Signed and sealed this 19th day of May 1970 ISEAL) kttest:

Ward M. Fletcher, Jr. WILLIAM SCHIIYLER, JR.

Lttesting Officer Commissioner of Patents 

